Diet can effect this. A lot of “natural” products are less healthy for some people because of allergies. You are probably removing too much of your natural oil by washing too much or scrubbing too hard. Your skin will take care of itself, you just need to help it out a little with gentle scrubbing, good nutrition, a little sun, etc..
If you think you’ve got an infection or something like that, you shouldn’t be such a stickler about using only “natural” products. The problems that come from using the synthetic crap are from long term use, mostly. And there may be some drugs that can help. Get it checked out by a dermatologist if you can.
You shouldn’t need any product, natural or not, to keep your scalp healthy in the long term. Don’t build a dependence on one if you can help it.